//! Graphical front-end (`pixelpass --gui`), compiled only with the `gui`
//! feature.
//!
//! Architecture: this window is a thin **shell-out** driver. It never touches
//! the capture / portal / gst / iroh machinery directly — instead it re-execs
//! this same binary in headless mode (`pixelpass --host --output json …` or
//! `pixelpass <ticket> --output json`) as a child process and parses the
//! child's JSON event stream (see [`crate::common::output`]) to drive what it
//! shows. That keeps the fragile capture stack sealed in a separate process:
//! the GUI can be closed or crash without taking a live stream down.
//!
//! ## Windowing: why we hand-roll the loop instead of using `eframe`
//!
//! The "keep running in the tray" feature needs to truly *hide* the window
//! while a stream keeps running in the child. On Wayland there is no
//! unmap-but-keep-alive request in xdg-shell, so winit's `set_visible(false)`
//! is a deliberate no-op there — the only way to make a toplevel vanish is to
//! **destroy its surface** and recreate it later. `eframe::run_native` owns the
//! one window it will never let you drop, so we replace it with a hand-rolled
//! [`winit::application::ApplicationHandler`] + `glutin` + [`egui_glow`] loop:
//!
//!   * **Hide to tray** ([`Gfx::hide`]) parks the GL context as *not-current*
//!     and drops the [`winit::window::Window`] + its GL surface — the Wayland
//!     surface is genuinely gone, natively, on both Wayland and X11.
//!   * **Show** ([`Gfx::show`], on a tray click) recreates the window + surface
//!     and makes the parked context current again.
//!
//! The GL context, `glutin` display/config, and the `egui_glow` painter (with
//! its uploaded font/texture atlas) and `egui-winit` state (with its clipboard
//! connection) are **kept** across the cycle — only the OS window and its
//! surface churn. That preserves the hard-won Wayland clipboard integration and
//! avoids re-uploading textures on every show.
//!
//! Wakeups are routed through winit's [`winit::event_loop::EventLoopProxy`]
//! (see [`Waker`] and [`tray`]) rather than egui's repaint callback, because a
//! child event or tray click must wake the loop even while the window is
//! dropped and no egui frame is running.

mod child;
mod theme;
mod tray;

use std::num::NonZeroU32;
use std::sync::Arc;
use std::time::{Duration, Instant};

use eframe::egui;
use egui_glow::EguiGlow;
use egui_glow::egui_winit;
use egui_glow::glow::{self, HasContext as _};
use glutin::config::{Config, ConfigTemplateBuilder};
use glutin::context::{
    ContextApi, ContextAttributesBuilder, NotCurrentContext, NotCurrentGlContext as _,
    PossiblyCurrentContext, PossiblyCurrentGlContext as _,
};
use glutin::display::{Display, GetGlDisplay as _, GlDisplay as _};
use glutin::surface::{
    GlSurface as _, Surface, SurfaceAttributesBuilder, SwapInterval, WindowSurface,
};
use glutin_winit::{ApiPreference, DisplayBuilder};
use winit::application::ApplicationHandler;
use winit::event::WindowEvent;
use winit::event_loop::{ActiveEventLoop, ControlFlow, EventLoop, EventLoopProxy};
use winit::raw_window_handle::HasWindowHandle as _;
use winit::window::{Window, WindowAttributes, WindowId};

use self::child::{ChildEvent, ChildProc};
use self::tray::{TrayAction, TrayHandle, TrayStatus};

/// Initial / minimum window size, in logical points. Initial height fits the
/// host screen (ticket + Copy + QR + Stop) without needing to scroll on a 1080p
/// display; the host screen still wraps in a ScrollArea for the case where the
/// user shrinks the window below MIN_INNER_SIZE proportions.
const INNER_SIZE: [f64; 2] = [520.0, 640.0];
const MIN_INNER_SIZE: [f64; 2] = [460.0, 380.0];

/// Events delivered to the winit loop from off the UI thread (or from egui).
pub enum UserEvent {
    /// Something changed off the UI thread — a headless child emitted a JSON
    /// event or exited (see [`Waker`]). Drain it on the next tick, and repaint
    /// if a window is currently shown.
    Wake,
    /// A system-tray icon/menu action (see [`tray`]).
    Tray(TrayAction),
}

/// A cheap, cloneable handle that wakes the winit event loop from any thread.
///
/// Used by the headless-child reader threads: pinging this wakes the loop
/// **even when the window has been dropped to the tray** (no egui frame is
/// running then, so egui's own repaint callback would go quiet after the first
/// request — see the egui repaint bookkeeping). That's what keeps join/leave
/// desktop notifications and the tray tooltip live while hidden.
#[derive(Clone)]
pub struct Waker {
    proxy: EventLoopProxy<UserEvent>,
}

impl Waker {
    /// Wake the loop. A send error only means the loop has already exited, in
    /// which case there is nothing left to wake.
    pub fn wake(&self) {
        let _ = self.proxy.send_event(UserEvent::Wake);
    }
}

/// Window attributes used for both the first window and every recreated one, so
/// a window restored from the tray is identical to the original.
fn window_attributes() -> WindowAttributes {
    use winit::dpi::LogicalSize;
    // Wayland sources the titlebar/taskbar icon from the .desktop file matched
    // by this app_id (NOT from `with_window_icon`, which Wayland ignores) — it
    // must equal the installed pixelpass.desktop. `with_name(general, instance)`
    // sets the Wayland app_id to `general`.
    use winit::platform::wayland::WindowAttributesExtWayland as _;

    let mut attrs = WindowAttributes::default()
        .with_title("PixelPass")
        .with_inner_size(LogicalSize::new(INNER_SIZE[0], INNER_SIZE[1]))
        .with_min_inner_size(LogicalSize::new(MIN_INNER_SIZE[0], MIN_INNER_SIZE[1]))
        // Stay unmapped until the first frame is painted, to avoid a flash of an
        // empty window (on Wayland the surface only maps on the first swap
        // anyway; this matters mostly for X11).
        .with_visible(false)
        .with_name("pixelpass", "pixelpass");

    // X11 titlebar/taskbar icon (`_NET_WM_ICON`), embedded at compile time so
    // the binary stays self-contained. Wayland ignores it (uses app_id above);
    // X11 falls back to it. Non-fatal on failure.
    match eframe::icon_data::from_png_bytes(include_bytes!("../../assets/pixelpass-256.png")) {
        Ok(icon) => match winit::window::Icon::from_rgba(icon.rgba, icon.width, icon.height) {
            Ok(winit_icon) => attrs = attrs.with_window_icon(Some(winit_icon)),
            Err(e) => tracing::warn!("could not build X11 window icon: {e}"),
        },
        Err(e) => tracing::warn!("could not load embedded window icon: {e}"),
    }
    attrs
}

/// Build a GL surface for `window` using the established display + config.
fn create_surface(
    display: &Display,
    config: &Config,
    window: &Window,
) -> anyhow::Result<Surface<WindowSurface>> {
    let (w, h): (u32, u32) = window.inner_size().into();
    let attrs = SurfaceAttributesBuilder::<WindowSurface>::new().build(
        window.window_handle()?.as_raw(),
        NonZeroU32::new(w).unwrap_or(NonZeroU32::MIN),
        NonZeroU32::new(h).unwrap_or(NonZeroU32::MIN),
    );
    // SAFETY: `window` outlives the surface — both live in the same `WinState`
    // and are dropped together — so the raw handle stays valid for the
    // surface's lifetime.
    let surface = unsafe { display.create_window_surface(config, &attrs)? };
    Ok(surface)
}

/// GL + egui state that persists for the whole GUI session. Only the OS window
/// and its surface are dropped/recreated on hide/show (see the module docs);
/// everything here outlives the cycle.
struct Gfx {
    gl: Arc<glow::Context>,
    gl_display: Display,
    gl_config: Config,
    egui_glow: EguiGlow,
    /// egui→window command state (title changes etc.), threaded through
    /// [`egui_winit::process_viewport_commands`] each frame.
    viewport_info: egui::ViewportInfo,
    win: WinState,
}

/// Whether the window is currently mapped. The GL *context* is preserved in
/// both states; `Between` is only a momentary placeholder during a transition.
// Exactly one `WinState` exists (it's a field of the single `Gfx`), never a
// collection of them, so the inter-variant size gap costs ~250 idle bytes once
// — not worth boxing the window/surface that every frame touches.
#[allow(clippy::large_enum_variant)]
enum WinState {
    Shown {
        window: Window,
        surface: Surface<WindowSurface>,
        context: PossiblyCurrentContext,
    },
    Hidden {
        context: NotCurrentContext,
    },
    /// Transient placeholder held only inside [`Gfx::hide`] / [`Gfx::show`].
    Between,
}

impl Gfx {
    /// Full first-time initialization: pick a GL config, create the window,
    /// context, and surface, make the context current, and build the egui glow
    /// integration. Runs once, from `resumed`.
    fn create(event_loop: &ActiveEventLoop) -> anyhow::Result<Self> {
        let template = ConfigTemplateBuilder::new()
            .prefer_hardware_accelerated(None)
            .with_depth_size(0)
            .with_stencil_size(0)
            .with_transparency(false);

        let (maybe_window, gl_config) = DisplayBuilder::new()
            .with_preference(ApiPreference::FallbackEgl)
            .with_window_attributes(Some(window_attributes()))
            .build(event_loop, template, |mut configs| {
                configs.next().expect("no GL config matched")
            })
            .map_err(|e| anyhow::anyhow!("failed to choose a GL config: {e}"))?;

        let gl_display = gl_config.display();

        // On EGL/Wayland the window is built during `build`; on GLX it is
        // deferred until the visual is known, so finalize it here.
        let window = match maybe_window {
            Some(w) => w,
            None => glutin_winit::finalize_window(event_loop, window_attributes(), &gl_config)?,
        };

        let raw = window.window_handle()?.as_raw();
        let ctx_attrs = ContextAttributesBuilder::new().build(Some(raw));
        // Fall back to a GLES context if a core GL context can't be created.
        let gles_attrs = ContextAttributesBuilder::new()
            .with_context_api(ContextApi::Gles(None))
            .build(Some(raw));
        // SAFETY: `raw` comes from `window`, which lives at least as long as the
        // context (both are owned by this `Gfx`).
        let not_current = unsafe {
            gl_display
                .create_context(&gl_config, &ctx_attrs)
                .or_else(|_| gl_display.create_context(&gl_config, &gles_attrs))
        }
        .map_err(|e| anyhow::anyhow!("failed to create a GL context: {e}"))?;

        let surface = create_surface(&gl_display, &gl_config, &window)?;
        let context = not_current
            .make_current(&surface)
            .map_err(|e| anyhow::anyhow!("failed to make the GL context current: {e}"))?;
        // Vsync, so the frame loop self-throttles and idles cheaply.
        let _ = surface.set_swap_interval(&context, SwapInterval::Wait(NonZeroU32::MIN));

        // SAFETY: the loader is only called while `gl_display` is alive, which
        // outlives the returned context.
        let gl = Arc::new(unsafe {
            glow::Context::from_loader_function(|s| match std::ffi::CString::new(s) {
                Ok(name) => gl_display.get_proc_address(name.as_c_str()),
                Err(_) => std::ptr::null(),
            })
        });

        let egui_glow = EguiGlow::new(event_loop, gl.clone(), None, None, true);

        let mut fonts = egui::FontDefinitions::default();
        fonts.font_data.insert(
            "noto_sans".to_owned(),
            egui::FontData::from_static(include_bytes!("../../assets/NotoSans-Regular.ttf")).into(),
        );
        fonts
            .families
            .get_mut(&egui::FontFamily::Proportional)
            .unwrap()
            .insert(0, "noto_sans".to_owned());
        egui_glow.egui_ctx.set_fonts(fonts);

        let mut style = (*egui_glow.egui_ctx.global_style()).clone();
        for font_id in style.text_styles.values_mut() {
            font_id.size *= 1.25;
        }
        egui_glow.egui_ctx.set_global_style(style);

        window.set_visible(true);
        window.request_redraw();

        Ok(Self {
            gl,
            gl_display,
            gl_config,
            egui_glow,
            viewport_info: egui::ViewportInfo::default(),
            win: WinState::Shown {
                window,
                surface,
                context,
            },
        })
    }

    fn shown_window(&self) -> Option<&Window> {
        match &self.win {
            WinState::Shown { window, .. } => Some(window),
            _ => None,
        }
    }

    /// Hide to tray: park the context as not-current and drop the window +
    /// surface. The Wayland surface is genuinely destroyed (the only way to
    /// hide a toplevel there).
    fn hide(&mut self) {
        match std::mem::replace(&mut self.win, WinState::Between) {
            WinState::Shown {
                window,
                surface,
                context,
            } => match context.make_not_current() {
                Ok(not_current) => {
                    // Order matters: the context must be made not-current before
                    // its surface is dropped.
                    drop(surface);
                    drop(window);
                    self.win = WinState::Hidden {
                        context: not_current,
                    };
                }
                Err(e) => {
                    tracing::error!("hide-to-tray: make_not_current failed: {e}");
                    // Leave `Between` (window already gone); a later Show will
                    // log that there's no parked context and the user can quit
                    // from the tray. This effectively never happens.
                }
            },
            other => self.win = other, // already hidden / transient
        }
    }

    /// Restore from the tray: recreate the window + surface and make the parked
    /// context current again.
    fn show(&mut self, event_loop: &ActiveEventLoop) -> anyhow::Result<()> {
        match std::mem::replace(&mut self.win, WinState::Between) {
            WinState::Hidden { context } => {
                let window = glutin_winit::finalize_window(
                    event_loop,
                    window_attributes(),
                    &self.gl_config,
                )?;
                let surface = create_surface(&self.gl_display, &self.gl_config, &window)?;
                let context = context
                    .make_current(&surface)
                    .map_err(|e| anyhow::anyhow!("failed to make the GL context current: {e}"))?;
                let _ = surface.set_swap_interval(&context, SwapInterval::Wait(NonZeroU32::MIN));
                window.set_visible(true);
                window.request_redraw();
                self.win = WinState::Shown {
                    window,
                    surface,
                    context,
                };
                Ok(())
            }
            WinState::Shown {
                window,
                surface,
                context,
            } => {
                // Already shown — just nudge a repaint and restore.
                window.request_redraw();
                self.win = WinState::Shown {
                    window,
                    surface,
                    context,
                };
                Ok(())
            }
            WinState::Between => {
                anyhow::bail!("no parked GL context to restore the window from")
            }
        }
    }

    /// Run one egui frame and paint it. Returns how long egui wants to wait
    /// before the next repaint (`Duration::MAX` == idle, sleep until an event).
    /// No-op returning `MAX` if the window isn't currently shown.
    fn paint_frame(&mut self, run_ui: impl FnMut(&mut egui::Ui)) -> Duration {
        let WinState::Shown {
            window,
            surface,
            context,
        } = &self.win
        else {
            return Duration::MAX;
        };
        let eg = &mut self.egui_glow;

        let raw_input = eg.egui_winit.take_egui_input(window);
        let egui::FullOutput {
            platform_output,
            textures_delta,
            shapes,
            pixels_per_point,
            viewport_output,
        } = eg.egui_ctx.run_ui(raw_input, run_ui);

        eg.egui_winit
            .handle_platform_output(window, platform_output);

        // Apply any window commands egui emitted (we issue none directly, but
        // egui may request e.g. IME changes) and read the next repaint delay.
        let (repaint_delay, commands) = match viewport_output.get(&egui::ViewportId::ROOT) {
            Some(out) => (out.repaint_delay, out.commands.clone()),
            None => (Duration::MAX, Vec::new()),
        };
        if !commands.is_empty() {
            let mut actions = Vec::new();
            egui_winit::process_viewport_commands(
                &eg.egui_ctx,
                &mut self.viewport_info,
                commands,
                window,
                &mut actions,
            );
        }

        let clipped = eg.egui_ctx.tessellate(shapes, pixels_per_point);
        for (id, image_delta) in &textures_delta.set {
            eg.painter.set_texture(*id, image_delta);
        }

        let dimensions: [u32; 2] = window.inner_size().into();
        // SAFETY: the context is current (we are in the `Shown` arm) and `gl`
        // belongs to it.
        unsafe {
            self.gl.clear_color(0.08, 0.08, 0.08, 1.0);
            self.gl.clear(glow::COLOR_BUFFER_BIT);
        }
        eg.painter
            .paint_primitives(dimensions, pixels_per_point, &clipped);
        for id in &textures_delta.free {
            eg.painter.free_texture(*id);
        }

        if let Err(e) = surface.swap_buffers(context) {
            tracing::warn!("GL swap_buffers failed: {e}");
        }
        repaint_delay
    }
}

/// The winit application: owns the persistent GL/egui state ([`Gfx`]) and the
/// PixelPass UI logic ([`PixelPassApp`]), and routes events between them.
struct App {
    state: PixelPassApp,
    /// `None` until the first `resumed`; `Some` for the rest of the session
    /// (the window inside may be Shown or Hidden).
    gfx: Option<Gfx>,
    /// When the next repaint is due, derived from egui's per-frame delay and
    /// external wakes. `None` == idle (sleep until an event).
    repaint_at: Option<Instant>,
}

impl App {
    fn shown_window(&self) -> Option<&Window> {
        self.gfx.as_ref().and_then(Gfx::shown_window)
    }

    fn request_redraw(&self) {
        if let Some(w) = self.shown_window() {
            w.request_redraw();
        }
    }

    /// Run an egui frame now (if shown) and record the next repaint deadline.
    fn redraw(&mut self) {
        let App {
            gfx,
            state,
            repaint_at,
            ..
        } = self;
        let Some(gfx) = gfx.as_mut() else { return };
        let delay = gfx.paint_frame(|ui| state.draw(ui));
        *repaint_at = (delay < Duration::MAX).then(|| Instant::now() + delay);
    }

    /// The window's close button: hide to the tray if enabled and a tray is
    /// actually present, otherwise quit.
    fn on_close(&mut self, event_loop: &ActiveEventLoop) {
        let hide = self.state.close_to_tray
            && self.state.tray.as_ref().is_some_and(TrayHandle::registered);
        if hide {
            if let Some(gfx) = self.gfx.as_mut() {
                gfx.hide();
            }
            self.repaint_at = None;
        } else {
            event_loop.exit();
        }
    }
}

impl ApplicationHandler<UserEvent> for App {
    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
        if self.gfx.is_some() {
            return; // already initialized
        }
        match Gfx::create(event_loop) {
            Ok(gfx) => self.gfx = Some(gfx),
            Err(e) => {
                tracing::error!("GUI: could not create the window/GL context: {e}");
                event_loop.exit();
            }
        }
    }

    fn window_event(&mut self, event_loop: &ActiveEventLoop, _id: WindowId, event: WindowEvent) {
        if matches!(event, WindowEvent::CloseRequested) {
            self.on_close(event_loop);
            return;
        }
        if matches!(event, WindowEvent::RedrawRequested) {
            self.redraw();
            return;
        }
        if let WindowEvent::Resized(size) = &event
            && let Some(gfx) = self.gfx.as_ref()
            && let WinState::Shown {
                surface, context, ..
            } = &gfx.win
            && let (Some(w), Some(h)) = (NonZeroU32::new(size.width), NonZeroU32::new(size.height))
        {
            surface.resize(context, w, h);
        }

        // Feed the event to egui and repaint if it wants one.
        let Some(gfx) = self.gfx.as_mut() else { return };
        let WinState::Shown { window, .. } = &gfx.win else {
            return;
        };
        let response = gfx.egui_glow.egui_winit.on_window_event(window, &event);
        if response.repaint {
            window.request_redraw();
        }
    }

    fn user_event(&mut self, event_loop: &ActiveEventLoop, event: UserEvent) {
        match event {
            UserEvent::Wake => {
                // A child emitted/closed: update state (and fire notifications /
                // tray tooltip) even while hidden, then repaint if shown.
                self.state.tick();
                self.request_redraw();
            }
            UserEvent::Tray(TrayAction::Show) => {
                if let Some(gfx) = self.gfx.as_mut()
                    && let Err(e) = gfx.show(event_loop)
                {
                    tracing::error!("could not restore the window from the tray: {e}");
                }
                self.state.tick();
            }
            UserEvent::Tray(TrayAction::Quit) => {
                event_loop.exit();
            }
        }
    }

    fn about_to_wait(&mut self, event_loop: &ActiveEventLoop) {
        let flow = match self.repaint_at {
            None => ControlFlow::Wait,
            Some(at) if at > Instant::now() => ControlFlow::WaitUntil(at),
            Some(_) => {
                // Due now: ask for a frame if there's a window to paint into;
                // otherwise (hidden) drop the pending repaint and sleep.
                if let Some(w) = self.shown_window() {
                    w.request_redraw();
                } else {
                    self.repaint_at = None;
                }
                ControlFlow::Wait
            }
        };
        event_loop.set_control_flow(flow);
    }

    fn exiting(&mut self, _event_loop: &ActiveEventLoop) {
        // Release GL resources only if the context is current (window shown);
        // when hidden the context isn't current, and the process is exiting
        // anyway so the driver reclaims everything.
        if let Some(gfx) = self.gfx.as_mut()
            && matches!(gfx.win, WinState::Shown { .. })
        {
            gfx.egui_glow.painter.destroy();
        }
    }
}

/// Launch the GUI. Blocks until the window is closed (or the tray Quit is
/// chosen). Runs on the main thread, a winit requirement, which is where `main`
/// calls it from.
/// `relay` is the parent's `--relay` flag (if any), forwarded to every child
/// process so a relay chosen on the GUI command line reaches the headless
/// host/viewer. (The `PIXELPASS_RELAY` env var is inherited regardless; this
/// covers the flag form.)
pub fn run(relay: Option<String>) -> anyhow::Result<()> {
    let event_loop = EventLoop::<UserEvent>::with_user_event()
        .build()
        .map_err(|e| anyhow::anyhow!("failed to build the event loop: {e}"))?;
    event_loop.set_control_flow(ControlFlow::Wait);

    let proxy = event_loop.create_proxy();
    let waker = Waker {
        proxy: proxy.clone(),
    };
    // The tray runs on its own thread and wakes us via the proxy.
    let tray = tray::start(proxy.clone());
    let gui_settings = crate::common::config::load()
        .map(|c| c.gui)
        .unwrap_or_default();

    let active = theme::load_named(&gui_settings.theme);
    let names = theme::all_themes().into_iter().map(|t| t.name).collect();
    let draft = active.clone();

    let state = PixelPassApp {
        screen: Screen::default(),
        host: HostState::default(),
        viewer: ViewerState::default(),
        tray,
        close_to_tray: gui_settings.close_to_tray,
        show_qr: gui_settings.show_qr,
        relay,
        theme: ThemeState {
            active,
            names,
            dirty: true, // apply on the first frame
            editing: false,
            draft,
            status: None,
        },
        waker,
    };
    let mut app = App {
        state,
        gfx: None,
        repaint_at: None,
    };

    event_loop
        .run_app(&mut app)
        .map_err(|e| anyhow::anyhow!("GUI event loop error: {e}"))
}

/// Best-effort clipboard write. Returns whether it succeeded so callers can
/// show an honest "✓ Copied" / fallback hint (the clipboard can be flaky on
/// Wayland, and a silent miss is what left users pasting stale tickets).
fn set_clipboard(text: &str) -> bool {
    arboard::Clipboard::new()
        .and_then(|mut cb| cb.set_text(text.to_owned()))
        .is_ok()
}

/// Best-effort clipboard read, backing the viewer Paste button and the
/// View-screen prefill. `None` on a flaky/empty clipboard — callers just leave
/// the field untouched.
fn get_clipboard() -> Option<String> {
    arboard::Clipboard::new()
        .and_then(|mut cb| cb.get_text())
        .ok()
}

/// Decode the host endpoint id from a ticket string, using the exact same
/// parse the viewer does (`EndpointTicket::from_str`), so the GUI agrees with
/// the child about what's a valid code. `None` means it isn't a pixelpass
/// ticket at all. Used to surface a stale/garbage paste *before* the 15s
/// connect timeout, and to show which host the viewer is dialing — the missing
/// signal that let people repeatedly dial a long-dead host.
fn ticket_endpoint_id(ticket: &str) -> Option<String> {
    ticket
        .trim()
        .parse::<iroh_tickets::endpoint::EndpointTicket>()
        .ok()
        .map(|t| t.endpoint_addr().id.to_string())
}

/// Eyeball-comparable short form of an endpoint id (full ids are long). Enough
/// to spot that two ids differ; the host and viewer screens show the same
/// truncation so a stale ticket reads as an obvious mismatch.
fn short_id(id: &str) -> String {
    let prefix: String = id.chars().take(12).collect();
    if prefix.len() < id.len() {
        format!("{prefix}…")
    } else {
        prefix
    }
}

/// Fire a desktop notification, on a detached thread so the D-Bus round-trip
/// can't stall the egui frame. Best-effort: with no notification daemon it
/// just does nothing. (notify-rust talks D-Bus via pure-Rust zbus, so this
/// needs no system libdbus and no GTK event loop.)
fn notify(summary: &'static str, body: String) {
    std::thread::spawn(move || {
        if let Err(e) = notify_rust::Notification::new()
            .appname("PixelPass")
            .summary(summary)
            .body(&body)
            .show()
        {
            tracing::warn!("desktop notification failed: {e}");
        }
    });
}

/// Persist just the close-to-tray preference, preserving the rest of the
/// on-disk config (e.g. the bandwidth section the headless child may have
/// written). Best-effort: a write failure is logged, not surfaced.
fn persist_close_to_tray(value: bool) {
    let mut cfg = crate::common::config::load().unwrap_or_default();
    cfg.gui.close_to_tray = value;
    if let Err(e) = crate::common::config::save(&cfg) {
        tracing::warn!("failed to save settings: {e}");
    }
}

fn persist_show_qr(value: bool) {
    let mut cfg = crate::common::config::load().unwrap_or_default();
    cfg.gui.show_qr = value;
    if let Err(e) = crate::common::config::save(&cfg) {
        tracing::warn!("failed to save settings: {e}");
    }
}

fn persist_theme(name: &str) {
    let mut cfg = crate::common::config::load().unwrap_or_default();
    cfg.gui.theme = name.to_string();
    if let Err(e) = crate::common::config::save(&cfg) {
        tracing::warn!("failed to save settings: {e}");
    }
}

/// Which screen the single window is currently showing.
#[derive(Default, PartialEq)]
enum Screen {
    #[default]
    Menu,
    Host,
    Viewer,
    Settings,
}

/// Quality preset choices, mirroring `cli::Quality`. Map to the `--quality`
/// argument value passed to the child.
#[derive(Default, PartialEq, Clone, Copy)]
enum QualitySel {
    #[default]
    Auto,
    Source,
    High,
    Medium,
    Low,
}

impl QualitySel {
    fn as_arg(self) -> &'static str {
        match self {
            QualitySel::Auto => "auto",
            QualitySel::Source => "source",
            QualitySel::High => "high",
            QualitySel::Medium => "medium",
            QualitySel::Low => "low",
        }
    }

    fn label(self) -> &'static str {
        match self {
            QualitySel::Auto => "Auto — pick from my upload speed",
            QualitySel::Source => "Source — native resolution",
            QualitySel::High => "High — up to 1080p",
            QualitySel::Medium => "Medium — up to 720p",
            QualitySel::Low => "Low — up to 480p",
        }
    }

    const ALL: [QualitySel; 5] = [
        QualitySel::Auto,
        QualitySel::Source,
        QualitySel::High,
        QualitySel::Medium,
        QualitySel::Low,
    ];
}

/// Player choices for the viewer screen.
#[derive(Default, PartialEq, Clone, Copy)]
enum PlayerSel {
    #[default]
    Mpv,
    Vlc,
}

impl PlayerSel {
    fn to_player(self) -> crate::interactive::Player {
        match self {
            PlayerSel::Mpv => crate::interactive::Player::Mpv,
            PlayerSel::Vlc => crate::interactive::Player::Vlc,
        }
    }
}

/// Host-screen state: the config form fields plus, once started, the running
/// child and the latest values parsed from its event stream.
#[derive(Default)]
struct HostState {
    // form
    quality: QualitySel,
    max_viewers: u32, // 0 = let the host auto-size from the bandwidth preflight
    no_hwencode: bool,
    window: bool,
    // running session + accumulated live state
    proc: Option<ChildProc>,
    ticket: Option<String>,
    info: Option<HostInfo>,
    active: u32,
    max: u32,
    capturing: bool,
    /// Whether the current ticket made it onto the clipboard (auto-copy on
    /// arrival, or a manual Copy click). Drives the "✓ Copied" hint so the
    /// user isn't left guessing whether to click Copy — the trap that had
    /// people pasting a stale clipboard ticket.
    copied: bool,
    last_refusal: Option<String>,
    error: Option<String>,
    /// Endpoint ids of the currently-connected viewers, in arrival order.
    /// Drives the per-viewer list and its Kick buttons.
    viewers: Vec<String>,
    /// QR-code rendering of the current ticket, lazily built on the first draw
    /// after a Ticket event lands. Cleared on session start/stop so the next
    /// session's ticket regenerates it.
    qr_texture: Option<egui::TextureHandle>,
}

/// The host config summary echoed back by the child's `host_info` event.
struct HostInfo {
    display: String,
    capture: String,
    quality: String,
    dimensions: String,
    hw_encode: bool,
    cap_source: String,
}

/// Viewer-screen state.
#[derive(Default)]
struct ViewerState {
    ticket_input: String,
    player: PlayerSel,
    proc: Option<ChildProc>,
    url: Option<String>,
    launched: bool,
    /// Short endpoint id we're dialing, decoded from the ticket at Connect.
    /// Shown in the "Connecting to …" line so a dead host is identifiable.
    connecting_to: Option<String>,
    /// Set when the View screen opens so the code field grabs focus once
    /// (cleared on use, so it doesn't steal focus every frame).
    focus_ticket: bool,
    error: Option<String>,
}

/// The PixelPass UI logic — screens, the running children, and the tray. Knows
/// nothing about windowing; [`App`] drives its [`PixelPassApp::draw`] each frame
/// and [`PixelPassApp::tick`] on each wake.
struct PixelPassApp {
    screen: Screen,
    host: HostState,
    viewer: ViewerState,
    /// System-tray handle; `None` if the tray couldn't start, in which case the
    /// close button always quits (never hides).
    tray: Option<TrayHandle>,
    /// Persisted preference: when true (and a tray is present), the close button
    /// hides to the tray instead of quitting. Loaded at startup, written on
    /// toggle in Settings.
    close_to_tray: bool,
    /// Persisted preference: render the QR-code panel on the host screen.
    /// Defaults to on; toggled in Settings.
    show_qr: bool,
    /// The parent's `--relay` flag, forwarded to host/viewer children so the
    /// flag form reaches them (env-var form is inherited automatically).
    relay: Option<String>,
    /// The active colour theme (applied to egui's visuals) and the supporting
    /// picker/editor state.
    theme: ThemeState,
    /// Wakes the winit loop when a spawned child emits/exits.
    waker: Waker,
}

/// The active theme plus the Settings picker/editor working state.
struct ThemeState {
    /// Currently applied theme (persisted by name in the config).
    active: theme::Theme,
    /// Theme names shown in the picker, refreshed when Settings opens so files
    /// added on disk appear without a restart.
    names: Vec<String>,
    /// Set when `active` needs (re)applying to egui's visuals.
    dirty: bool,
    /// Whether the in-app editor is open. While open its `draft` is applied as a
    /// live preview instead of `active`; closing without saving restores `active`.
    editing: bool,
    /// The editor's working copy.
    draft: theme::Theme,
    /// Last save result or error, shown under the editor.
    status: Option<String>,
}

/// Apply `theme`'s palette to egui's visuals, preserving the font scaling and
/// fonts already baked into the global style (we replace only `visuals`).
fn apply_theme(ctx: &egui::Context, theme: &theme::Theme) {
    let mut style = (*ctx.global_style()).clone();
    style.visuals = theme.visuals();
    ctx.set_global_style(style);
}

/// One row of the theme editor: a label and a colour picker. Theme colours are
/// opaque, so any alpha the picker introduces is clamped straight back out.
fn color_row(ui: &mut egui::Ui, label: &str, color: &mut egui::Color32) {
    ui.label(label);
    ui.color_edit_button_srgba(color);
    let [r, g, b, _] = color.to_srgba_unmultiplied();
    *color = egui::Color32::from_rgb(r, g, b);
    ui.end_row();
}

impl PixelPassApp {
    /// Drain child output and reflect it into the tray. Runs on every wake,
    /// whether or not a window is shown, so notifications and the tray tooltip
    /// stay live while hidden.
    fn tick(&mut self) {
        self.pump_host_events();
        self.pump_viewer_events();
        self.sync_tray_status();
    }

    /// Render the current screen. Called from inside the egui frame.
    fn draw(&mut self, ui: &mut egui::Ui) {
        // Apply whichever theme should be visible this frame. While the editor
        // is open its draft is previewed live; otherwise the active theme is
        // applied once (when dirty) and then sticks — the egui context persists
        // across the hide/show window cycle, so it survives close-to-tray.
        if self.theme.editing {
            apply_theme(ui.ctx(), &self.theme.draft);
        } else if self.theme.dirty {
            apply_theme(ui.ctx(), &self.theme.active);
            self.theme.dirty = false;
        }
        match self.screen {
            Screen::Menu => self.menu(ui),
            Screen::Host => self.host(ui),
            Screen::Viewer => self.viewer(ui),
            Screen::Settings => self.settings(ui),
        }
    }

    /// Mirror current activity into the tray icon's tooltip/menu.
    fn sync_tray_status(&mut self) {
        let status = if self.host.proc.is_some() {
            TrayStatus::Hosting {
                active: self.host.active,
                max: self.host.max,
            }
        } else if self.viewer.proc.is_some() {
            TrayStatus::Viewing
        } else {
            TrayStatus::Idle
        };
        if let Some(tray) = &mut self.tray {
            tray.set_status(status);
        }
    }

    fn menu(&mut self, ui: &mut egui::Ui) {
        ui.vertical_centered(|ui| {
            ui.add_space(24.0);
            ui.heading("PixelPass");
            ui.label("P2P screen sharing");
            ui.label(
                egui::RichText::new(concat!("v", env!("CARGO_PKG_VERSION")))
                    .small()
                    .weak(),
            );
            ui.add_space(32.0);
            if ui
                .add_sized([260.0, 40.0], egui::Button::new("Host — share my screen"))
                .clicked()
            {
                self.screen = Screen::Host;
            }
            ui.add_space(8.0);
            if ui
                .add_sized(
                    [260.0, 40.0],
                    egui::Button::new("View — watch someone's screen"),
                )
                .clicked()
            {
                self.screen = Screen::Viewer;
                self.prefill_viewer_ticket();
            }
            ui.add_space(20.0);
            if ui.button("⚙ Settings").clicked() {
                // Refresh the picker so themes added to the folder since launch
                // (or last visit) show up without a restart.
                self.theme.names = theme::all_themes().into_iter().map(|t| t.name).collect();
                self.screen = Screen::Settings;
            }
        });
    }

    fn settings(&mut self, ui: &mut egui::Ui) {
        ui.horizontal(|ui| {
            if ui.button("← Menu").clicked() {
                self.screen = Screen::Menu;
            }
            ui.heading("Settings");
        });
        ui.separator();
        // Body scrolls; the header above stays pinned. The Appearance editor
        // (13 colour rows + Save) overflows a short window otherwise — you'd
        // have to resize the window to reach the Save button.
        egui::ScrollArea::vertical().show(ui, |ui| self.settings_body(ui));
    }

    fn settings_body(&mut self, ui: &mut egui::Ui) {
        ui.add_space(4.0);

        let resp = ui.checkbox(
            &mut self.close_to_tray,
            "Keep running in the tray when I close the window",
        );
        if resp.changed() {
            persist_close_to_tray(self.close_to_tray);
        }

        ui.add_space(4.0);
        ui.label(
            egui::RichText::new(
                "Off: closing the window quits PixelPass.\n\
                 On: closing hides it to the system tray and any active stream \
                 keeps running — reopen it from the tray icon.",
            )
            .small()
            .weak(),
        );

        ui.add_space(12.0);
        let qr_resp = ui.checkbox(&mut self.show_qr, "Show QR-code panel on the host screen");
        if qr_resp.changed() {
            persist_show_qr(self.show_qr);
        }
        ui.add_space(4.0);
        ui.label(
            egui::RichText::new(
                "Off: the host screen shows only the ticket text. \
                 Useful when both ends are computers and the QR is just extra clutter.",
            )
            .small()
            .weak(),
        );

        // The option does nothing without a tray to hide into; say so plainly.
        if !self.tray.as_ref().is_some_and(TrayHandle::registered) {
            ui.add_space(8.0);
            ui.colored_label(
                self.theme.active.warning,
                "⚠ No system tray detected — this option has no effect right now.",
            );
        }

        ui.add_space(16.0);
        ui.separator();
        ui.add_space(4.0);
        self.appearance(ui);
    }

    /// The "Appearance" block of the Settings screen: the theme picker, or the
    /// in-app editor when it's open.
    fn appearance(&mut self, ui: &mut egui::Ui) {
        ui.heading("Appearance");
        ui.add_space(6.0);

        if self.theme.editing {
            self.theme_editor(ui);
            return;
        }

        // Theme picker. Collect any selection first so we're not holding an
        // immutable borrow of `self.theme.names` when we mutate `self.theme`.
        let current = self.theme.active.name.clone();
        let mut pick: Option<String> = None;
        ui.horizontal(|ui| {
            ui.label("Theme");
            egui::ComboBox::from_id_salt("theme_picker")
                .selected_text(&current)
                .show_ui(ui, |ui| {
                    for name in &self.theme.names {
                        if ui.selectable_label(*name == current, name).clicked() {
                            pick = Some(name.clone());
                        }
                    }
                });
        });
        if let Some(name) = pick {
            self.select_theme(&name);
        }

        ui.add_space(8.0);
        if ui.button("✎ Edit / create a theme").clicked() {
            self.start_theme_edit();
        }
        ui.add_space(4.0);
        ui.label(
            egui::RichText::new(
                "Themes live as .toml files in your config folder \
                 (themes/). Drop one in to share or install it.",
            )
            .small()
            .weak(),
        );
        if let Some(status) = &self.theme.status {
            ui.add_space(4.0);
            ui.label(egui::RichText::new(status).small().weak());
        }
    }

    /// The in-app theme editor: a colour picker per palette field with a live
    /// preview, plus Save (writes a .toml) / Cancel.
    fn theme_editor(&mut self, ui: &mut egui::Ui) {
        ui.horizontal(|ui| {
            ui.label("Name");
            ui.text_edit_singleline(&mut self.theme.draft.name);
        });
        ui.checkbox(
            &mut self.theme.draft.dark,
            "Dark base (sets the fallback for anything the palette doesn't name)",
        );
        ui.add_space(6.0);

        egui::Grid::new("theme_editor_grid")
            .num_columns(2)
            .spacing([12.0, 6.0])
            .show(ui, |ui| {
                let d = &mut self.theme.draft;
                color_row(ui, "Window background", &mut d.window_bg);
                color_row(ui, "Panel background", &mut d.panel_bg);
                color_row(ui, "Input background", &mut d.input_bg);
                color_row(ui, "Text", &mut d.text);
                color_row(ui, "Secondary text", &mut d.weak_text);
                color_row(ui, "Accent", &mut d.accent);
                color_row(ui, "Button", &mut d.button_bg);
                color_row(ui, "Button (hover)", &mut d.button_hovered);
                color_row(ui, "Streaming", &mut d.streaming);
                color_row(ui, "Waiting", &mut d.waiting);
                color_row(ui, "Success", &mut d.success);
                color_row(ui, "Warning", &mut d.warning);
                color_row(ui, "Error", &mut d.error);
            });

        ui.add_space(10.0);
        ui.horizontal(|ui| {
            if ui.button("💾 Save").clicked() {
                self.save_draft_theme();
            }
            // Reset the draft to the original Default Dark palette. Previews
            // live (the editor applies the draft each frame), so it snaps back
            // immediately; Save persists it, Cancel discards.
            if ui.button("↺ Defaults").clicked() {
                self.theme.draft = theme::default_dark();
                self.theme.status = Some("Reset to the Default Dark palette.".to_string());
            }
            if ui.button("Cancel").clicked() {
                self.cancel_theme_edit();
            }
        });
        ui.add_space(4.0);
        ui.label(
            egui::RichText::new(
                "Changes preview live. Save writes a .toml to your themes folder; \
                 rename it to keep a built-in alongside your own version.",
            )
            .small()
            .weak(),
        );
        if let Some(status) = &self.theme.status {
            ui.add_space(4.0);
            ui.label(egui::RichText::new(status).small().weak());
        }
    }

    /// Switch to the named theme: apply it, persist the choice, and reset the
    /// editor draft to match.
    fn select_theme(&mut self, name: &str) {
        self.theme.active = theme::load_named(name);
        self.theme.draft = self.theme.active.clone();
        self.theme.dirty = true;
        self.theme.status = None;
        persist_theme(name);
    }

    fn start_theme_edit(&mut self) {
        self.theme.draft = self.theme.active.clone();
        self.theme.editing = true;
        self.theme.status = None;
    }

    fn cancel_theme_edit(&mut self) {
        self.theme.editing = false;
        self.theme.draft = self.theme.active.clone();
        self.theme.dirty = true; // discard the live preview, restore the active theme
        self.theme.status = None;
    }

    fn save_draft_theme(&mut self) {
        if self.theme.draft.name.trim().is_empty() {
            self.theme.status = Some("Give the theme a name before saving.".to_string());
            return;
        }
        match theme::save_theme(&self.theme.draft) {
            Ok(path) => {
                self.theme.active = self.theme.draft.clone();
                self.theme.editing = false;
                self.theme.dirty = true;
                self.theme.names = theme::all_themes().into_iter().map(|t| t.name).collect();
                self.theme.status = Some(format!("Saved to {}", path.display()));
                persist_theme(&self.theme.active.name);
            }
            Err(e) => self.theme.status = Some(format!("Couldn't save: {e}")),
        }
    }

    // ── Host screen ──────────────────────────────────────────────────────

    fn host(&mut self, ui: &mut egui::Ui) {
        let running = self.host.proc.is_some();
        ui.horizontal(|ui| {
            // Leaving the host screen stops the session (Drop on the child).
            if ui.button("← Menu").clicked() {
                self.stop_host();
                self.screen = Screen::Menu;
            }
            ui.heading("Host");
        });
        ui.separator();

        // Scroll the body, not the header — Menu/Host stay pinned at the top.
        // Needed once the QR panel landed: ticket + Copy + QR + Stop overflows a
        // shrunken window.
        egui::ScrollArea::vertical().show(ui, |ui| {
            if running {
                self.host_running(ui);
            } else {
                self.host_form(ui);
            }
        });
    }

    fn host_form(&mut self, ui: &mut egui::Ui) {
        if let Some(err) = &self.host.error {
            ui.colored_label(self.theme.active.error, err);
            ui.add_space(8.0);
        }

        egui::Grid::new("host_form")
            .num_columns(2)
            .spacing([12.0, 10.0])
            .show(ui, |ui| {
                ui.label("Quality");
                egui::ComboBox::from_id_salt("quality")
                    .selected_text(self.host.quality.label())
                    .show_ui(ui, |ui| {
                        for q in QualitySel::ALL {
                            ui.selectable_value(&mut self.host.quality, q, q.label());
                        }
                    });
                ui.end_row();

                ui.label("Max viewers");
                ui.horizontal(|ui| {
                    ui.add(egui::DragValue::new(&mut self.host.max_viewers).range(0..=16));
                    if self.host.max_viewers == 0 {
                        ui.label("(auto from upload speed)");
                    }
                });
                ui.end_row();

                ui.label("Options");
                ui.vertical(|ui| {
                    ui.checkbox(&mut self.host.window, "Share a single window");
                    ui.checkbox(
                        &mut self.host.no_hwencode,
                        "Software encoding (no GPU / VAAPI)",
                    );
                });
                ui.end_row();
            });

        ui.add_space(16.0);
        if ui
            .add_sized([160.0, 36.0], egui::Button::new("Start hosting"))
            .clicked()
        {
            self.start_host();
        }
        ui.add_space(8.0);
        ui.label(
            egui::RichText::new(
                "On Wayland a \"Share Screen?\" dialog appears when the first \
                 viewer connects.",
            )
            .small()
            .weak(),
        );
    }

    fn host_running(&mut self, ui: &mut egui::Ui) {
        if self.host.capturing {
            ui.colored_label(self.theme.active.streaming, "● Streaming");
        } else if self.host.ticket.is_some() {
            ui.colored_label(self.theme.active.waiting, "● Waiting for viewers…");
        } else {
            ui.label("Starting…");
        }

        ui.add_space(6.0);
        ui.label(format!("Viewers: {} / {}", self.host.active, self.host.max));

        // Per-viewer list with a Kick button each. Collect the click first so
        // we're not borrowing self.host.viewers while we reach for the child.
        let mut kick: Option<String> = None;
        for id in &self.host.viewers {
            ui.horizontal(|ui| {
                ui.label(format!("• endpoint {}", short_id(id)));
                if ui.small_button("Kick").clicked() {
                    kick = Some(id.clone());
                }
            });
        }
        if let Some(id) = kick
            && let Some(p) = &mut self.host.proc
        {
            p.send_command(&format!("kick {id}"));
        }

        if let Some(info) = &self.host.info {
            ui.label(
                egui::RichText::new(format!("{} · {}", info.display, info.capture))
                    .small()
                    .weak(),
            );
            ui.label(
                egui::RichText::new(format!(
                    "{} · {} · {} · cap {}",
                    info.quality,
                    info.dimensions,
                    if info.hw_encode {
                        "HW encode"
                    } else {
                        "software encode"
                    },
                    info.cap_source
                ))
                .small()
                .weak(),
            );
        }

        ui.add_space(12.0);

        if let Some(ticket) = self.host.ticket.clone() {
            ui.label("Share this code with your viewer(s):");
            if let Some(id) = ticket_endpoint_id(&ticket) {
                // The viewer shows "Connecting to <id>…" with this same
                // truncation, so the two ends can be eyeballed for a match.
                ui.label(
                    egui::RichText::new(format!("This host: endpoint {}", short_id(&id)))
                        .small()
                        .weak(),
                );
            }
            ui.add_space(4.0);
            egui::Frame::group(ui.style()).show(ui, |ui| {
                ui.add(
                    egui::Label::new(egui::RichText::new(&ticket).monospace().small())
                        .wrap()
                        .selectable(true),
                );
            });
            ui.add_space(4.0);
            ui.horizontal(|ui| {
                if ui.button("📋 Copy code").clicked() {
                    self.copy_to_clipboard(&ticket);
                }
                if self.host.copied {
                    ui.colored_label(self.theme.active.success, "✓ Copied to clipboard");
                }
            });
            if !self.host.copied {
                ui.label(
                    egui::RichText::new(
                        "Couldn't auto-copy — click Copy, or select the code above.",
                    )
                    .small()
                    .weak(),
                );
            }

            // Lazy QR build: first draw after a Ticket event has `qr_texture =
            // None`, so we encode the ticket and load the texture once. The
            // 4-module quiet zone (white border) matters — phone scanners reject
            // QR codes flush against a non-white edge. Skipped when the user
            // disabled the QR panel in Settings.
            if self.show_qr
                && self.host.qr_texture.is_none()
                && let Ok(code) = qrcode::QrCode::new(ticket.as_bytes())
            {
                let w = code.width();
                let quiet = 4;
                let full = w + 2 * quiet;
                let colors = code.into_colors();
                let mut pixels = vec![egui::Color32::WHITE; full * full];
                for y in 0..w {
                    for x in 0..w {
                        if colors[y * w + x] == qrcode::Color::Dark {
                            pixels[(y + quiet) * full + (x + quiet)] = egui::Color32::BLACK;
                        }
                    }
                }
                let img = egui::ColorImage::new([full, full], pixels);
                self.host.qr_texture = Some(ui.ctx().load_texture(
                    "host_qr",
                    img,
                    egui::TextureOptions::NEAREST,
                ));
            }
            if self.show_qr
                && let Some(tex) = &self.host.qr_texture
            {
                ui.add_space(8.0);
                ui.add(egui::Image::new(tex).fit_to_exact_size(egui::vec2(200.0, 200.0)));
            }
        }

        if let Some(reason) = &self.host.last_refusal {
            ui.add_space(8.0);
            ui.colored_label(self.theme.active.warning, format!("⚠ {reason}"));
        }

        ui.add_space(16.0);
        if ui
            .add_sized([140.0, 36.0], egui::Button::new("Stop hosting"))
            .clicked()
        {
            self.stop_host();
        }
    }

    fn start_host(&mut self) {
        self.host.error = None;
        self.host.last_refusal = None;
        self.host.ticket = None;
        self.host.info = None;
        self.host.active = 0;
        self.host.max = 0;
        self.host.capturing = false;
        self.host.copied = false;
        self.host.viewers.clear();
        self.host.qr_texture = None;

        let mut args = vec![
            "--host".to_string(),
            "--output".to_string(),
            "json".to_string(),
            "--quality".to_string(),
            self.host.quality.as_arg().to_string(),
        ];
        if self.host.max_viewers > 0 {
            args.push("--max-viewers".to_string());
            args.push(self.host.max_viewers.to_string());
        }
        if self.host.no_hwencode {
            args.push("--no-hwencode".to_string());
        }
        if self.host.window {
            args.push("--window".to_string());
        }
        if let Some(relay) = &self.relay {
            args.push("--relay".to_string());
            args.push(relay.clone());
        }

        match ChildProc::spawn(&args, self.waker.clone()) {
            Ok(p) => self.host.proc = Some(p),
            Err(e) => self.host.error = Some(format!("Couldn't start host: {e}")),
        }
    }

    fn stop_host(&mut self) {
        // Dropping the ChildProc SIGINTs the child and reaps it.
        self.host.proc = None;
        self.host.capturing = false;
        self.host.ticket = None;
        self.host.copied = false;
        self.host.viewers.clear();
        self.host.qr_texture = None;
    }

    /// Drain the host child's event channel into state, and detect an
    /// unexpected child exit (e.g. a failed dependency check) so it surfaces
    /// in the form instead of leaving a dead "running" view.
    fn pump_host_events(&mut self) {
        let events: Vec<ChildEvent> = match &self.host.proc {
            Some(p) => std::iter::from_fn(|| p.rx.try_recv().ok()).collect(),
            None => return,
        };
        for ev in events {
            self.apply_host_event(ev);
        }

        if let Some(p) = &mut self.host.proc
            && !p.is_alive()
        {
            if self.host.ticket.is_none() {
                let tail = p.stderr_tail();
                self.host.error = Some(if tail.trim().is_empty() {
                    "Host exited before it could start.".to_string()
                } else {
                    format!("Host exited before it could start:\n{tail}")
                });
            }
            self.host.proc = None;
            self.host.capturing = false;
        }
    }

    fn apply_host_event(&mut self, ev: ChildEvent) {
        match ev {
            ChildEvent::Ticket { value } => {
                // Auto-copy on arrival, mirroring the CLI/interactive host
                // (which copies the ticket and prints "copied to your
                // clipboard"). A failure here is non-fatal: the ticket stays
                // visible for manual copy, and `copied` stays false so the UI
                // doesn't falsely claim success.
                self.host.copied = set_clipboard(&value);
                self.host.ticket = Some(value);
            }
            ChildEvent::HostInfo {
                display_server,
                capture,
                quality,
                dimensions,
                hw_encode,
                max_viewers,
                max_viewers_source,
            } => {
                self.host.max = max_viewers;
                self.host.info = Some(HostInfo {
                    display: display_server,
                    capture,
                    quality,
                    dimensions,
                    hw_encode,
                    cap_source: max_viewers_source,
                });
            }
            ChildEvent::ViewerJoined { id, active, max } => {
                self.host.active = active;
                self.host.max = max;
                if !self.host.viewers.contains(&id) {
                    notify(
                        "PixelPass — viewer connected",
                        format!(
                            "endpoint {} is now watching ({active}/{max})",
                            short_id(&id)
                        ),
                    );
                    self.host.viewers.push(id);
                }
            }
            ChildEvent::ViewerLeft { id, active, max } => {
                self.host.active = active;
                self.host.max = max;
                if self.host.viewers.iter().any(|v| v == &id) {
                    notify(
                        "PixelPass — viewer disconnected",
                        format!("endpoint {} left ({active}/{max})", short_id(&id)),
                    );
                    self.host.viewers.retain(|v| v != &id);
                }
            }
            ChildEvent::Capture { state } => {
                self.host.capturing = matches!(state, child::CaptureState::Started);
            }
            ChildEvent::ViewerRefused { reason } => self.host.last_refusal = Some(reason),
            ChildEvent::Connected { .. } => {} // viewer-side; not used on the host screen
        }
    }

    /// Manual Copy-button handler: copy and reflect success in the UI, or
    /// surface a clear error if the clipboard rejected it.
    fn copy_to_clipboard(&mut self, text: &str) {
        if set_clipboard(text) {
            self.host.copied = true;
            self.host.error = None;
        } else {
            self.host.copied = false;
            self.host.error = Some(
                "Couldn't write to the clipboard. Select the code above and copy it manually."
                    .to_string(),
            );
        }
    }

    // ── Viewer screen ─────────────────────────────────────────────────────

    fn viewer(&mut self, ui: &mut egui::Ui) {
        let running = self.viewer.proc.is_some();
        ui.horizontal(|ui| {
            if ui.button("← Menu").clicked() {
                self.stop_viewer();
                self.screen = Screen::Menu;
            }
            ui.heading("View");
        });
        ui.separator();

        if running {
            self.viewer_running(ui);
        } else {
            self.viewer_form(ui);
        }
    }

    fn viewer_form(&mut self, ui: &mut egui::Ui) {
        if let Some(err) = &self.viewer.error {
            ui.colored_label(self.theme.active.error, err);
            ui.add_space(8.0);
        }

        ui.label("Paste the share code you received:");
        ui.add_space(4.0);
        // A Paste button (read-side mirror of the host's Copy button — one
        // click grabs the code the host just put on the clipboard) with the
        // field filling the rest of the row. A single horizontal row, so it
        // doesn't grab the panel's full height.
        let ticket_resp = ui
            .horizontal(|ui| {
                if ui.button("📋 Paste").clicked()
                    && let Some(text) = get_clipboard()
                {
                    self.viewer.ticket_input = text.trim().to_string();
                }
                ui.add(
                    egui::TextEdit::singleline(&mut self.viewer.ticket_input)
                        .desired_width(f32::INFINITY)
                        .hint_text("endpoint…"),
                )
            })
            .inner;
        // Grab focus once on screen entry so the user can paste/type straight
        // away without first clicking into the field.
        if std::mem::take(&mut self.viewer.focus_ticket) {
            ticket_resp.request_focus();
        }
        // Enter in the field connects (gated on a decodable code below).
        let enter_pressed =
            ticket_resp.lost_focus() && ui.input(|i| i.key_pressed(egui::Key::Enter));

        // Decode the pasted code live: confirms it's a real ticket and shows
        // which host it points at, so a stale clipboard paste is caught here
        // instead of after the 15s connect timeout.
        let trimmed = self.viewer.ticket_input.trim().to_string();
        let decoded_id = ticket_endpoint_id(&trimmed);
        if !trimmed.is_empty() {
            ui.add_space(4.0);
            match &decoded_id {
                Some(id) => ui.colored_label(
                    self.theme.active.success,
                    format!("→ endpoint {}", short_id(id)),
                ),
                None => ui.colored_label(
                    self.theme.active.warning,
                    "⚠ This doesn't look like a share code.",
                ),
            };
        }

        ui.add_space(10.0);
        ui.horizontal(|ui| {
            ui.label("Player");
            egui::ComboBox::from_id_salt("player")
                .selected_text(match self.viewer.player {
                    PlayerSel::Mpv => "mpv",
                    PlayerSel::Vlc => "VLC",
                })
                .show_ui(ui, |ui| {
                    ui.selectable_value(&mut self.viewer.player, PlayerSel::Mpv, "mpv");
                    ui.selectable_value(&mut self.viewer.player, PlayerSel::Vlc, "VLC");
                });
        });

        ui.add_space(16.0);
        // Only dial a code that actually decodes — no point spawning a child to
        // spend 15s timing out against garbage. Enter takes the same path.
        let connect_clicked = ui
            .add_enabled(
                decoded_id.is_some(),
                egui::Button::new("Connect").min_size(egui::vec2(140.0, 36.0)),
            )
            .on_disabled_hover_text("Paste a valid share code first.")
            .clicked();
        if decoded_id.is_some() && (connect_clicked || enter_pressed) {
            self.start_viewer();
        }
    }

    fn viewer_running(&mut self, ui: &mut egui::Ui) {
        if self.viewer.launched {
            ui.colored_label(self.theme.active.streaming, "● Streaming");
            ui.label("Player launched. Close it or disconnect to stop.");
        } else if self.viewer.url.is_some() {
            ui.label("Connected — launching player…");
        } else {
            let msg = match &self.viewer.connecting_to {
                Some(id) => format!("● Connecting to {id}…"),
                None => "● Connecting…".to_string(),
            };
            ui.colored_label(self.theme.active.waiting, msg);
        }

        ui.add_space(16.0);
        if ui
            .add_sized([140.0, 36.0], egui::Button::new("Disconnect"))
            .clicked()
        {
            self.stop_viewer();
        }
    }

    /// On entering the View screen, drop a clipboard ticket straight into the
    /// field — the host's Copy button (and our auto-copy) usually leaves the
    /// freshly-shared code right there. Guarded so it only fires when the field
    /// is empty and the clipboard holds a *decodable* ticket, so stray
    /// clipboard text never lands in the box; the live decode still shows the
    /// id for the user to verify.
    fn prefill_viewer_ticket(&mut self) {
        if self.viewer.ticket_input.trim().is_empty()
            && self.viewer.proc.is_none()
            && let Some(text) = get_clipboard()
            && ticket_endpoint_id(&text).is_some()
        {
            self.viewer.ticket_input = text.trim().to_string();
        }
        self.viewer.focus_ticket = true;
    }

    fn start_viewer(&mut self) {
        self.viewer.error = None;
        self.viewer.url = None;
        self.viewer.launched = false;

        let ticket = self.viewer.ticket_input.trim().to_string();
        self.viewer.connecting_to = ticket_endpoint_id(&ticket).map(|id| short_id(&id));
        let mut args = vec![ticket, "--output".to_string(), "json".to_string()];
        if let Some(relay) = &self.relay {
            args.push("--relay".to_string());
            args.push(relay.clone());
        }
        match ChildProc::spawn(&args, self.waker.clone()) {
            Ok(p) => self.viewer.proc = Some(p),
            Err(e) => self.viewer.error = Some(format!("Couldn't connect: {e}")),
        }
    }

    fn stop_viewer(&mut self) {
        self.viewer.proc = None;
        self.viewer.url = None;
        self.viewer.launched = false;
        self.viewer.connecting_to = None;
    }

    fn pump_viewer_events(&mut self) {
        let events: Vec<ChildEvent> = match &self.viewer.proc {
            Some(p) => std::iter::from_fn(|| p.rx.try_recv().ok()).collect(),
            None => return,
        };
        for ev in events {
            if let ChildEvent::Connected { url } = ev {
                self.viewer.url = Some(url.clone());
                if !self.viewer.launched {
                    match self.viewer.player.to_player().spawn(&url) {
                        Ok(()) => self.viewer.launched = true,
                        Err(e) => self.viewer.error = Some(format!("Couldn't launch player: {e}")),
                    }
                }
            }
        }

        if let Some(p) = &mut self.viewer.proc
            && !p.is_alive()
        {
            // Bridge ended (player closed) or the connection failed.
            if self.viewer.url.is_none() {
                let tail = p.stderr_tail();
                self.viewer.error = Some(if tail.trim().is_empty() {
                    "Couldn't connect to the host (check the code).".to_string()
                } else {
                    format!("Connection ended:\n{tail}")
                });
            }
            self.viewer.proc = None;
            self.viewer.launched = false;
            self.viewer.url = None;
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    /// A real, parseable ticket built the same way the host builds one
    /// (`EndpointTicket::new`), from a deterministic key so the id is stable.
    fn sample_ticket() -> (String, String) {
        let sk = iroh::SecretKey::from_bytes(&[7u8; 32]);
        let id = sk.public().to_string();
        let ticket =
            iroh_tickets::endpoint::EndpointTicket::new(iroh::EndpointAddr::new(sk.public()))
                .to_string();
        (ticket, id)
    }

    #[test]
    fn decodes_endpoint_id_from_a_valid_ticket() {
        let (ticket, id) = sample_ticket();
        assert_eq!(ticket_endpoint_id(&ticket).as_deref(), Some(id.as_str()));
    }

    #[test]
    fn tolerates_surrounding_whitespace() {
        let (ticket, _) = sample_ticket();
        assert!(ticket_endpoint_id(&format!("  \n{ticket}\t ")).is_some());
    }

    #[test]
    fn rejects_non_ticket_input() {
        // The empty/whitespace/garbage cases that gate the Connect button off.
        assert_eq!(ticket_endpoint_id(""), None);
        assert_eq!(ticket_endpoint_id("   "), None);
        assert_eq!(ticket_endpoint_id("hello world"), None);
        assert_eq!(ticket_endpoint_id("endpointbutnotreally"), None);
    }

    #[test]
    fn short_id_truncates_long_ids() {
        assert_eq!(short_id("0123456789abcdefghij"), "0123456789ab…");
    }

    #[test]
    fn short_id_leaves_short_or_exact_ids_intact() {
        assert_eq!(short_id("abc"), "abc");
        assert_eq!(short_id("0123456789ab"), "0123456789ab"); // exactly 12, no ellipsis
    }
}